Numerical analysis of the blasting damaged zone in tunnel using UDEC

Despite many improvement in the underground construction by mechanized ‎methods and the whole section, the drilling and blasting still plays an important ‎role in the construction of tunnels and mines. In addition to various advantages ‎such as flexibility and low capital cost, this method also has disadvantages, one of ‎which is the expansion of the blast damage zone around the underground ‎structure, which leads to increased joints and cracks in the surrounding ‎environment and consequently reduced resistance and increased permeability ‎also In some cases land subsidence occurs . Various factors affect the damage ‎zone. Various methods such as measurement, experimental and modeling ‎methods are available to investigate these factors. In this paper, numerical ‎modeling has been done for three different state of drilling a. In addition to a brief ‎mention of different factors affecting the damage zone, it is determined that the ‎maximum impact on the damage area is related to tensile strength and cohesion ‎of rock. In addition, the effect of rock geological strength index (GSI) has been ‎investigated as one of the important factors in recognizing rock mass and the ‎effect of reducing the damage area with increasing GSI has been observed.‎